Straight edge system for drafting tables



J. D. GAYER Julie 10, 1958 STRAIGHT EDGE SYSTEM FOR DRAFTING TABLES Filegl June 17, 1954 3 Sheets-Sheet 1 INVENTOR.

JOHN D. GAYER ATTORNEYS June 1958 J, b, AYER 2,837,827

STRAIGHT EDGE SYSTEM FOR DRAFTING TABLES Filed June 17, 1954 3 Sheets-Sheet 2 14-5 FIG-4 103109 l -s 35 sz 55 IIL f INVENTOR. JOHN D. GAYER ATTORNEYS June 10, 1958 J. D. GAYER STRAIGHT EDGE SYSTEM FOR DRAFTING TABLES Filed June 17, 1954 3 Sheets-Sheet 5 INVEVTOR.

, JOHN D. GAYER ATTORNEYS nited States Patent STRAIGHT EDGE SYSTEM FOR DRAFTING TABLES This invention relates to drafting straight edge systems.

In preparing drawings, especially large detail views which require the drawing of lines exactly parallel or at specific angles to a common base line or center line, the draftsman must depend to a great deal upon the accuracy of his straight edge system to maintain a surface which can be moved up and down along the board to furnish a reference line which is always parallel to the base line or center line. On the other hand, it is not advisable to mount the straight edge so that it can only move parallel to one edge of the drafting board, for example the top edge, since it is much simpler when making corrections or additions on an existing drawing to align the straight edge with the drawing rather than vice versa. Especially is this so when working on large drawings which are several times the size of the drawing table and most unwieldy to handle.

Further, it is not uncommon to tilt the drawing board at a substantial angle, and in such positions the straight edge must be held in place as it is moved to a desired spot on the board, since its own weight will draw it downwardly toward the bottom edge of the board.

It is a primary object of this invention to provide a drafting straight edge system which will accurately maintain the straight edge parallel to a reference line on a drawing during movement of the straight edge up and down the drawing table, while permitting adjustment relative to the board of the straight edge to conform it initially to the reference lines of a drawing.

Another object of this invention is to provide a straight edge system wherein movement of the straight edge up and down the board is counterbalanced to offset the tendency of the straight edge to creep toward the bottom of the board when the upper edge of the board is elevated.

, A further object of this invention is to provide a straight edge system for a drawing. board including tape members arranged to move each end of the straight edge an equal distance up or downthe board relative to a drawing, and wherein the tape members extend along opposite sides of the board and are spaced from these sides to permit a continuous sheet of drawing larger in area than the working surface of the board to be worked upon with-. out'interfere'nce to the straight edge system.

It is also an object of the present invention to provide a straight edge system for a drawing board wherein tape members are arranged along each side of the board to coordinate movement of each end of the straight edge, and wherein the straight edge is so hinged to the tape members as to permit easy removal of the straight edge for cleaning thereof and for access to the entire working surface.

Otherobjects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawing- Fig. 1 is a perspective view of a drawing board equipped "ice ' with the straight edge system provided by this invention;

Fig. 2 is a plan view of Fig. l with certain portions broken away for clarity;

Fig. 3 is a side view of Fig. 2 with the outer casing of the straight edge system removed;

Fig. 4 is a partial section taken along line 4--4 of Fig. 3;

Fig. 5 is a partial section of a modified construction which may be used in place of the device seen in Fig. 4;

Fig. 6 is a partial section taken along line 66 of Fig. 2;

Fig. 7 is an enlarged detail view of the straight edge hinge connection seen in Fig. 2;

Fig. 8 is a section taken along line 8-8 of Fig. 7;

Fig. 9 is a section taken along line 9-9 of Fig. 7;

Fig. 10 is a section taken along line 10 -10 of Fig. 7;

Fig. 11 is a partial plan view of a modified system which may be used in conjunction with the straight edge system seen in Fig. 2; and

Fig. 12 is a perspective view of another type of tape which may be employed in place of the perforated tape seen in Figs. 3 and 11.

Referring to the drawings, which illustrate preferred embodiments of the invention, and particularly to Figs. 1 and 2, there is seen a drawing board 20 having an upper edge 22, a lower edge 23 and opposite sides indicated at 24. This board. is supported by a suitable base 25, which base generally provides for adjustment of the surface of the board 20 from horizontal to an acute angle to the horizontal. The straight edge system provided by the present invention includes brackets 30 which are. fastened to the sides 24 of the drawing board, as by screws 30a, so as to project from the upper and lower corners thereof to support the straight edge system. Each pair, of brackets at one side of the board includes spacer members 31 to which are secured inner casings 32 including upper and lower lip portions 33 extending along the entire side of the board in spaced relationship thereto, and projecting beyond the upper corners of the board for a 'short distance and beyond the lower corners for a somewhat greater distance. Outer casing members '34, having cooperating lip portions 35, are arranged to be fitted over the inner casings 32 and fastened, as by screws 36, to spacers 31. The inner and outer casings contact each other only at the corner of the board, so that a space in the form of slots 38 extends along substantially the entire length of the casings.

Astraight edge 40 extends transversely across the entire board 20, and is mounted for movement between the upper and lower edges of board 20 by hinge members 42 fastened to each of its opposite ends. These hinge members are so proportion-ed as to extend over the space between the sides 24 ofthe board to a point immediately ab'ove'inner casings 32. The movement of straight edge 48 up and down boardZti is coordinated at each end'so as to maintain the straight edge parallel to a reference line on a drawing fixed to the board duringv such movement.- This-coordinationis provided by a pair of hinge members indicated broadly at 44 (Fig. 4) as having narrow I-shaped portions 45 extending through slots 38, and also having suitable connections, indicated generally at 47, with hinge members 42 on the straight edge. The lower'portion of each hinge member 44 is securely fastened to the center of one of a pair of bands or tapes 59, each of'which are pierced at equally spaced intervals over substantially their entire lengths to provide tooth receiving perforations 51.

By controlling the movement of tapes 59 relative to each other'it is possible to move hinge members 44 up i and down along the sides of board 20 throughthe same distance, thus holding the parallel setting of straight edge 40 during movement thereof up and down the board. To accomplish this coordination of the tapes, a pair of upper sprocket wheels 52 and a pair of lower sprocket wheels 54 aremounted respectively-at each upper and lower end of inner casings 32, with their protruding teeth 55 adapted to be received in successive perforations 51 as the tapes are progressively fed over sprocket wheels 52 and 54. A cross shaft 60 extends along the upper edge 22 and is journaled in extended portions 61 of the upper spacers by means of suitable bearings 62 and 63. Collars 65 are fixed about shaft 60, for example by means of set screws 66, immediately adjacent extended portions 61 to prevent transverse shifting of shaft 60 within the bearings once the shaft is set in place, thus preventing misalignment of sprocket wheels 52 with tapes 50.

At each end of shaft 60 suitable attaching means, for example screws 67 threaded into a tapped portion at the ends of the shaft (Fig. 6), are provided to fix the sprocket wheels 52 to the opposite ends of shaft 60 for rotation therewith. The lower sprocket wheels 54 are mounted for free rotation in the lower ends of casings 32-34, for example on stub shafts 69 (Fig. 2). In assembly the tapes 50, with hinge members 44 attached, are threaded around sprocket wheels 52 and 54 to permit teeth 55 to protrude through perforations 51, and the free ends of the tapes are then secured together to complete loops at each side of the board within the casings.

These loops are completed by securing opposite ends of each tape 50 to opposite portions 70 and 72 of a slit counterweight, as best seen at 73 in Fig. 3. Since there is one of these counterweights in each loop, the total weight of portions 70 and 72 on one side need only be approximately equal to one half the weight of straight edge 40 and its associated hinge members 42 and 44. The counterweight portions 70 and 72 are joined with set screws '75, by means of which the gap between these portions can be regulated, and since opposite ends of tape 50 are attached to each one of these portions, the tension of the tape is likewise regulated.

A stub shaft 77 is mounted transversely through the larger counterweight portion 70 and carries a pair of rubber tired wheels 78 on opposite sides of the counterweight, to provide support therefor and to reduce friction to a minimum during sliding movement of the counterweight up and down within casings 32-34 when the straight edge is moved down or up the board and these wheels ride upon the lower lip portions 33 and 35 of the respective inner and outer casings 32 and 34. To prevent any possible entanglement of the loop, and also to maintain the correct spacing of slot 38, an L-shaped channel member 80 is provided within the casings, which channel member has its leg portion 81 suitably secured to the inner side wall of casing 32. This channel member extends completely across the inside of the casing and rests against the inner side wall of outer casing 34 when the latter is in place, thus providing an accurate spacing between the two casing members, and also dividing the inner space between these two casing members into an upper channel, wherein the upper portion of the loop including hinge member 44 may travel, and a lower chamber wherein counterweight and the remainder of the loop may travel in opposition to the upper portion thereof.

Referring to Fig. 5, there is shown a modification of this spacing and counterweight support system wherein a counterweight portion 70' may be provided with two stub shafts 85 and 86 which each have received thereon rubber tired wheels 87 and 88 respectively, the wheel 87 being set at an angle in an under cut portion 89 of counterweight 70 so as to ride upon the very corner of lip portion 33. Also in this modification, an L-shaped bracing channel 90 .has its leg portion 91 secured to t he inner side wall of outer casing 35, providing the same 4 spacing and strengthening effects as channel 80, and also affording a track for wheel 88.

If desired, additional weights may be added to the counterweight system, should it be necessary for the straight edge to continually support certain drafting tools when the table is inclined to horizontal. To provide for such weights, an elongated stud 95 is secured in any suitable manner to counterweight portion 70', and this stud includes an enlarged or flattened head 96 upon which additional weights may be hung.

As mentioned above, it is desirable to provide for alignment of the straight edge with a reference line on a drawing, and to accomplish this the hinging connection on at least one end of straight edge 40 is constructed so as to be movable relative to tape 50. In the drawing only the right hand connection is shown as incorporating this adjustment feature, but it is of course understood that both hinge connections could be made adjustable if desired.

Referring to Figs. 7-10, the hinge connection 47 is shown in detail as including a hinge pin 100 which is slidably received through an extended portion 102 of hinge member 42.. A dove-tail strip 104 is secured to the top of I-shaped portion 45, and overlying this dovetail strip is a slide member 105 which is doubly grooved at 107 and 108 to rest upon the top of member 45 and be slidable therealong without contacting the dove-tail strip 104, and which is bored at 106 to receive the end of hinge pin 100. That segment of pin 100 extending beyond the extended hinge portion 102 is reduced in diameter, as shown at 103. This reduced segment 103 extends into the outer end of bore 106, and terminates in a generally ball-shaped end 109 which is of the same diameter as the major portion of pin 100. The annular edges of end 109 are rounded to provide for a pivoting movement of end 109 Within bore 106, thereby providing for a small degree of misalignment between the longitudinal axes of pin 100 and bore 106, and thus allowing the pin to pivot about end 109 within the bore to an extent sufiicient to provide for a slight movement of the hinge member 42 relative to tape 50. The pin structure in the hinge member 42 at the other side of the board is identical with that just described. Referring particularly to Fig. 8, it will be noted that the extended hinge portion 102 and the bore hole 106 are elevated from the working surface of drawing board 20, thereby supporting the bottom or trailing edge of straight edge 40 above the board surface to minimize frictional contact between the straight edge and the drawing board, and to minimize smudging or smearing of the drawings by the lower surface of the straight edge. Upon movement of the straight edge 40 up or down the board only the upper or forward portion of the straight edge 40 contacts the board, as best seen in Fig. 8, and if desired it is easily possible to elevate the entire straight edge by pivoting it about hinge pins 100 so that it will clear the drawing completely during such movement up or down the board.

The slide 105 is vertically bored at 110 to a diameter approximately equal to the width of groove 107, so as to receive a locking device for preventing movement of the slide relative to dove-tail strip 104. This locking device includes a cylindrical stub 112 which is fitted into bore 110 for rotation therein, and which is provided with a dove-tail groove 113 across its bottom to embrace a cross section of strip 104 for frictional engagement thereof. An arm 115 is fixed to the top of stub 112 and extendsover slide 105 to adjacent pin 100, at which point the arm terminates in a portion 117 extending downwardly from one side of the arm. A suitable compression spring 118 is received in a small relief bore 119 provided in slide 105 immediately adjacent bore 106, and this spring abuts the downwardly extending portion 117 to urge it away from pin 100, thus twisting stub 112 within bore hole 110 and causing the walls of dove-tail groove 113 to press firmly against strip 104. Manual pressure on portion 117 against the spring 118 allows the dove-tail groove and strip to be aligned, permitting movement of slide 105 relative to I-shaped member 45.

In making alterations or additions to an existing drawing, the sheet is placed upon the board with the center or reference line thereon approximately aligned with straight edge 40. The draftsman then can apply pressure to arm 115, releasing slide 105 for movement relative to member 42, and pivot the straight edge about the ends of the pins 100 until it is properly and accurately aligned with the reference line.

Referring to Fig. 11, there is illustrated a modified device provided by this invention for permitting alignment of the straight edge with a reference-line. This device includes a shaft 120 mounted for transverse sliding movement at the top of board 20 in a pair of brackets 122 which are fixed to the top edge 22 of the board. A knurled operating knob 123 is fixed to the center of shaft 120 between brackets 122 to provide gripping means for sliding the shaft within the brackets. The opposite ends of shaft 120 have formed thereon opposite right and left hand spiral splines 125 and 126 respectively which are received in cooperating sockets formed in the inner ends of a pair of stub shafts 130 and 131. Each of these shafts is provided with a suitable collar 133 and is journaled within spacers 31 and attached to the respective upper sprocket wheels 52 in the same manner as shaft 60 (Fig. 6). i

In the device of Fig.7 the hinging connections between the straight edge 40 and tapes 50 need not be adjustable since this device provides for turning of upper sprocket wheels 52 relative to each other, thus altering the positions of opposite hinge members 42, and permitting for alignment of straight edge 40 with a desired reference line. This adjustment is effected bygrasping knob 123 and urging it to the right or left as desired, causing stub shafts 130131 to telescopically receive their respective spirals 125 and 126 and rotate in opposition to each other. Due to the relatively long, gradual configurations of the spirals, rotation of both sprocket wheels 52, upon movement of the straight edge up or down the board and consequent movement of tapes 50, will result in a force component which is substantially at right angles to the spiral splines and will not alter their setting.

Referring to Fig. 12, there is shown a modified type of sprocket and tape which may be found desirable in certain applications to replace the perforated metal tapes 50 seen in Figs. 3 and 11. This modified tape 140 comprises a belt which has a plurality of evenly spaced teeth 42 formed thereon. Suitable mating sprocket wheels 143 having a tooth configuration which matches the spacing of the teeth 142 will then be employed instead of the upper and lower sprocket wheels 52 and 54 respectively. In all other respectst he application of the tape 140 to the present invention is the same as that of tapes 50.

It will be seen that the presenti nvention provides a straight edge system which accurately maintains the straight edge parallel to any desired reference line on a drawing, yet permits movement of the straight edge with respect to the mechanism which controls its parallel movement for alignment of the straight edge with the drawing, thus -avoiding the necessity of moving the drawing once it is placed on the board. Referring to Figs. 1 and 3, it will be noted that a pair of straps 145 may be secured to the lower lip portions 33 of the inner casings. These straps are shaped to form loops which extend inwardly beneath the spacing between inner casings 32 and sides 24 of the board. When working on very large drawings, it is possible for the draftsman to roll the drawing, indicated at 150 in Figs. 1 and 4, at one side of the board and place it in the supporting loops provided by straps 145, and to work the drawing from one side to the other of the board, rolling the finished or corrected portion of the drawing at the opposite side from the initial roll. In the same manner, it is possible to maintain a roll of fresh drawing paper at one side of the board and feed appropriate lengths from such roll onto the board when making a series of smaller drawings.

Further, elongation of brackets 30 and casings 32 beyond the bottom edge 23 of the board permits movement of straight edge 40 to a lowermost portion, indicated in dotted lines at the left of Fig. 3, wherein substantially all of the straight edge is removed from the working surface of the board, and wherein the lead edge thereof may be used for drawing purposes adjacent the very bottom of the drawing. This added feature is most desirable since it eliminates the necessity for working the lowermost portions of a drawing with the trailing edge of the straight edge, whereby a substantial portion of the adjacent work, to which reference is often necessary, is covered by the body of the straight edge.

While the forms of apparatus herein described con stitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. In a drafting straight edge system comprising a drawing board and a straight edge extending entirely across said board, the combination of means for coordinating the movements of each end of said straight edge including tape members having respective center portions, hinge members attached to said center portions and operatively connected to opposite ends of said straight edge, said hinge members providing for pivotal movement of said straight edge toward and away from said board about an axis parallel to the length of said straight edge, upper and lower sprocket wheels supported adjacent each upper and lower corner of said board to operatively engage said tape members, counterweight means connecting the ends of each of said tape members to form closed loops at each side of said board and adapted to move parallel to the sides of said board in opposition to movement of said straight edge, a shaft connecting said upper sprocket wheels to coordinate rotation thereof and maintain said straight edge parallel to a reference line during movement of said straight edge up or down said board, and means for altering the alignment of said straight edge with respect to the reference line.

2. In combination with a drafting board and a straight edge extending across said board, sprocket wheels mounted for free rotation adjacent each corner of said board, a shaft mounted across the upper edge of said board and connected to the sprocket wheels at the upper corners thereof to coordinate rotation of said wheels, substantially non-elastic tape members extending parallel to the sides of said board and operatively engaging the sprocket wheels at the corners thereof, said tape members having center portions including hinge members attached to opposite ends of said straight edge, said hinge members providing for pivotal movement of said straight edge toward and away from said board about an axis parallel to the length of said straight edge, at least one of said hinge members being adjustable along to the longitudinal axis of its associated tape member, and a plurality of counterweights substantially equal in total weight to the weight of said straight edge, each of said counterweights being attached between opposite ends of each of said tape members to complete loops at each side of said board for maintaining said straight edge parallel to a reference line.

3. In a drafting straight edge system, a drawing board having opposite parallel sides and a top edge substantially perpendicular to said sides, a straight edge extending entirely across said board, inner casings supported in spaced parallel relationship to each of said opposite sides, upper and lower sprocket wheels supported for rotation at the ends of each said casing, tape members attached to the ends of said straight edge and extending substantially parallel to said casings to operatively engage said upper and lower sprocket wheels, means for joining the ends of said tape members to complete loops at each side of said board including counterweights movable in opposition to said straight edge for holding said straight edge in a selected position on said board, means for adding to the mass of said counterweights, lip portions on each said inner casing turned outwardly from said board to provide runways, and wheels mounted on said counterweights adapted to be received in said runways to support said counterweights for movementopposite to movement of said straight edge.

4. In combination with a drawing board and a straight edge having upper and lower parallel edges and extending entirely across said board, means for coordinating the movements of each end of said straight edge including tape members extending parallel to opposite sides of said board, hinge members secured to each said tape member, complementary hinge plates attached to the adjacent said lower edge of said straight edge, hinge pins operatively connecting said hinge plates and said hinge members to allow pivoting of said straight edge about its said lower edge upwardly away from said board and arranged to support said lower edge spaced above said board, upper and lower sprocket wheels supported adjacent each upper and lower corner of said. board to operatively engage said tape members, a shaft connecting said upper sprocket wheels to coordinate rotation thereof, means connecting the ends of said tape members to form closed loops at each side of said board, and means for altering the alignment of said straight edge with respect to a reference line on said board 5. In a drafting straight edge system, a drawing board having opposite parallel sides and a top edge substantially perpendicular to said sides, a straight edge extending entirely across said board, inner casings supported in spaced parallel relationship to each of said opposite sides to permit overlapping of a drawing between the sides of said board and said inner casings, means for supporting the ends of a drawing beneath said casings, upper and lower sprocket wheels supported for rotation at the ends of each said casing, perforated tape members having center portions attached to the ends of said straight edge and extending substantially parallel to said casings to operatively engage said upper and lower sprocket wheels, means for joining the ends of said tape members to complete loops at each side of said board including counterweights movable in opposition to said straight edge for holding said straight edge in a selected position on said board, lip portions on each said inner casing turned outwardly from said board to provide runways, wheels mounted on said counterweights and adapted to be received in said runways to support said counterweights for movement opposite to movement of said straight edge, and outer casings receivable on said inner casings to substantially enclose said loops.

6. In a drafting straight edge system, a drawing board having opposite parallel sides and a top edge substantially perpendicular to said sides, a straight edge extending entirely across said board, casings supported in spaced parallel relationship to each of said opposite sides, upper and lower sprocket wheels supported for rotation at the ends of each said casing, tape members attached to the ends of said straight edge and extending substantially parallel to said casings to operatively engage said upper and lower sprocket wheels, means for joining the ends of said tape members to complete loops at each side of said board including counterweights movable in opposition to said straight edge for holding said straight edge in a selected position on said board, lip portions on each said casing turned outwardly from said board to provide runways, and wheels mounted on said counterweights adapted to be received in said runways to support said counterweights for movement opposite to movement of said straight edge.

References Cited in the file of this patent UNITED STATES PATENTS 964,773 Guillo July 19, 1910 1,374,363 Davis Apr. 12, 1921 2,129,457 Von Zimmermann Sept. 6, 1938 2,520,021 Veyretet al Aug. 22, 1950 2,701,918 Phelps Feb. 15, 1955 FOREIGN PATENTS 6,674 Great Britain Mar. 16, 1905 317,382 Germany Dec. 16, 1919 438,807 Germany Dec. 28, 1926 

